Fluid dispenser and lens inspection device

ABSTRACT

A fluid dispenser dispenses a fluid alternately from one of a pair of ports ( 29,31 ) that are provided on opposite ends of a syringe ( 26 ) by moving a piston ( 42 ) back and forth inside the syringe. A pair of stirrers ( 47,48 ) are provided in the syringe on opposite axial sides of the piston. The stirrers may each individually rotate on an axis that extends in parallel with the moving direction of the piston. A pair of stirrer driving rings ( 49,50 ) are mounted on an outer periphery of the syringe in correspondence with the stirrers. Magnets ( 55,56,59,60 ) are embedded in the stirrers and the stirrer driving rings such that the stirrer is rotated by magnetic fields that are generated from the stirrer driving ring, as the stirrer driving ring is rotated by a motor ( 51,52 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a fluid dispenser that dispensesliquid or fluid from a container, called a syringe, by rising internalpressure of the syringe by a piston. More particularly, the presentinvention relates to a fluid dispenser for a lubricant containing solidmaterials, especially for a lubricant sprayed on a reused shuttermechanism before inspecting the shutter speed. The present inventionrelates also to a lens inspection system, especially for use inrecycling reused lenses.

[0003] 2. Background Arts

[0004] An exemplar of a well-known dispenser is disclosed in JapaneseLaid-open Patent Application No. 10-309456, that has a syringepartitioned by a piston into two chambers. By driving the piston toreciprocate inside the syringe, a liquid contained in the syringe isdispensed alternately from both chambers. While the liquid is beingejected from one of the chambers, the other chamber is beingsupplemented with the liquid. Thus, the dispenser of this type candispense the liquid in continuous succession. Where the liquid todispense is a lubricant that contains solid components, the lubricantmust continually be mixed or agitated for keeping the liquid densityconstant, because the solid components would otherwise precipitate. Forthis reason, it is necessary to provide a mixing mechanism in thesyringe in that case.

[0005] Japanese Laid-open Patent Application No. 10-146553 discloses anadhesive coating apparatus, wherein a mixing device is provided in asyringe for keeping the viscosity of a fluid adhesive material constant.The syringe has an ejection port on the bottom side. The fluid adhesivematerial is pushed by compressed air toward the ejection port, to beejected from the ejection port. The mixing device is constituted of anagitating propeller mounted on one end of a drive shaft. The other endof the drive shaft protrudes outside the syringe through a top openingthereof, and is driven to rotate the propeller by an external drivingforce.

[0006] Introducing such a mixing device into the above mentioneddispenser involves a problem that the drive shaft would interfere with apiston rod. To avoid this problem, the drive shaft must be inserted intothe syringe through a different position from where the piston rod isinserted. Then a complicated sealing device would be needed for closinga clearance between the drive shaft and the syringe, and thus increasesthe cost of the dispenser.

SUMMARY OF THE INVENTION

[0007] In view of the foregoing, an object of the present invention isto provide a fluid dispenser that can successively dispense a liquidwhile mixing the liquid continuously in a syringe, has a simplestructure and may be manufactured at a low cost.

[0008] According to an aspect of the present invention, in a fluiddispenser having a syringe with ports on opposite ends thereof, a pistonmovable inside said syringe back and forth, and a supply tank beingconnectable alternately to one of said ports depending upon movingdirection of said piston, said fluid dispenser dispensing a fluid fromone of said ports that is located on the end of said syringe towardwhich said piston is moving, while sucking the fluid from said supplytank into said syringe through the other of said ports, the fluiddispenser is characterized by comprising: a pair of stirrers providedrespectively in the chambers, the stirrers being rotatable on a rotaryaxis that extends parallel to the moving direction of the piston; and apair of stirrer driving devices disposed on an outer periphery of thesyringe in correspondence with the stirrers, for driving the stirrers torotate each individually by a magnetic force.

[0009] Since the stirrers are rotated by the magnetic force, there is noproblem about the interference of a drive shaft for the stirrer with apiston rod.

[0010] The stirrers have the same configuration, and have a plurality ofmagnets embedded therein symmetrically about the rotary axis of thestirrers, whereas the stirrer driving devices generate magnetic fieldsthat cause the stirrers to rotate. At least one of the stirrers iscontinuously rotated on one side of the piston, into which the liquid isbeing sucked.

[0011] A piston rod that moves together with the piston extends fromopposite end faces of the piston concentrically with the piston and thesyringe, and the piston is moved by a piston driving device that iscoupled to an end of the piston rod. According to a preferredembodiment, the stirrers are mounted on the piston rod so as to be ableto rotate around and slide along the piston rod. In this embodiment, thestirrers are kept in the same axial positions in the syringe by themagnetic forces of the stirrer driving device, even while the piston rodis being moved back and forth together with the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other objects and advantages of the presentinvention will become apparent from the following detailed descriptionof the preferred embodiments when read in association with theaccompanying drawings, which are given by way of illustration only andthus are not limiting the present invention. In the drawings, likereference numerals designate like or corresponding parts throughout theseveral views, and wherein:

[0013]FIG. 1 is a perspective view illustrating essential parts of alubricant coating system provided with a fluid dispenser according to anembodiment of the present invention;

[0014]FIG. 2 is an explanatory diagram illustrating the lubricantcoating system of FIG. 1 in a position at the end of a forward movementof a piston;

[0015]FIG. 3 is an explanatory diagram illustrating the lubricantcoating system of FIG. 1 in a position at the start of dispensingoperation by a backward movement of the piston;

[0016]FIG. 4 is a sectional perspective view of the fluid dispenser ofFIG. 1;

[0017]FIG. 5 is a sectional view of the fluid dispenser of FIG. 1;

[0018]FIG. 6 is a perspective view of a stirrer provided in a syringe ofthe fluid dispenser;

[0019]FIG. 7 is a sectional perspective view of the stirrer;

[0020]FIG. 8 is a sectional view of the dispenser taken along a lineVIII-VIII of FIG. 5;

[0021]FIG. 9 is a flow chart illustrating an automatic operationsequence of the lubricant coating system;

[0022]FIG. 10 is a flow chart illustrating a sequence of a normal modeof the lubricant coating system;

[0023]FIG. 11 is a flow chart illustrating a piston turning operation ofthe lubricant coating system;

[0024]FIG. 12 is an explanatory diagram illustrating the lubricantcoating system of FIG. 1 in a drip prevention step of the piston turningoperation;

[0025]FIG. 13 is an explanatory diagram illustrating the lubricantcoating system of FIG. 1 in a venting step of the piston turningoperation;

[0026]FIG. 14 is a flow chart illustrating a sequence of a standby modeof the lubricant coating system;

[0027]FIG. 15 is a flow chart illustrating a sequence of a recoveryoperation from the standby mode to the normal mode;

[0028]FIG. 16 is a fragmentary sectional view of a stirrer and a stirrerdriving device according to another embodiment of the present invention;

[0029]FIG. 17 is a block diagram illustrating a taking lens inspectionsystem according to another embodiment of the present invention;

[0030]FIG. 18 is a perspective view of a scratch detector of the takinglens inspection system of FIG. 17;

[0031]FIG. 19 is a perspective view of an extraneous object detector ofthe taking lens inspection system of FIG. 18;

[0032]FIG. 20 is a schematic diagram illustrating the scratch detectorof FIG. 18;

[0033]FIG. 21 is an explanatory diagram illustrating optical paths ofinspection light projected onto a lens having no scratch in the scratchdetector of FIG. 18;

[0034]FIG. 22 is an explanatory diagram illustrating optical paths ofinspection light projected onto a lens having a scratch in the scratchdetector of FIG. 18;

[0035]FIG. 23 is an explanatory diagram illustrating a light area in adark field image of the lens;

[0036]FIG. 24 is an explanatory sectional diagram illustrating theextraneous object detector of FIG. 19;

[0037]FIG. 25 is an explanatory diagram illustrating optical paths ofinspection light projected onto a lens having no scratch in theextraneous object detector of FIG. 19;

[0038]FIG. 26 is an explanatory diagram illustrating optical paths ofinspection light projected onto a lens having a scratch in theextraneous object detector of FIG. 19;

[0039]FIG. 27 is an explanatory diagram illustrating unit sections of aninspection range of an imaging device of the extraneous object detectorof FIG. 19;

[0040]FIG. 28 is a flow chart illustrating an overall sequence of ataking lens inspection process included in a process of recycling takinglenses of lens-fitted photo film unit; and

[0041]FIG. 29 is an explanatory diagram illustrating another pattern ofunit sections of the inspection range of the imaging device of theextraneous object detector.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In FIG. 1, a lubricant coating system 10 is constituted of acollection tank 11, a four-way switching valve 12, two-way switchingvalves 13 and 14, a supply tank 15, a dispenser 16, a needle valve 17and other minor elements. The dispenser 16 makes a dispensing operationto put a constant amount of lubricant on an object to coat 18 throughthe needle valve 17. In this instance, the lubricant is highly volatileand contains solid components.

[0043] The object to coat 18 is placed in a predetermined posture on apallet 19 and conveyed along a conveyer line 20. In a coating station,the pallet 19 is positioned by a positioning device, and the dispenser16 is activated upon receipt of an end-of-positioning signal from thepositioning device, to make the dispensing operation. The needle valve17 is disposed with its nozzle 17 a directed to a coating portion of theobject 18. After the coating of the object 18 is finished, thepositioning device releases the object upon receipt of an end-of-coatingsignal, so the coated object 18 is conveyed to the next process, and theobject to coat 18 is moved in the coating process.

[0044] As shown in FIG. 2, the needle valve 17 is provided with a on-offvalve 17 b for opening and closing the nozzle 17 a. The on-off valve 17b is actuated by compressed air that is supplied from a compressor 21.The on-off valve 17 b is usually set open. A cleaning mechanism 22 isdisposed in the vicinity of the nozzle 17 a. The cleaning mechanism 22uses the compressed air from the compressor 21, for blowing off thelubricant that is stuck to the nozzle 17 a.

[0045] Referring back to FIG. 1, the dispenser 16 is provided with a roddriving actuator 24, a piston rod 25 and a syringe 26, and controls theamount of movement of the piston rod 25 in one or another direction, todecide the amount of lubricant to be ejected through the needle valve17. The rod driving actuator 24 consists of a driving device, such as apulse motor, and a converter that converts a rotary force of the drivingdevice into reciprocation.

[0046] As shown in FIG. 2, a piston 42 is securely mounted on the pistonrod 25, and is moved back and forth inside the syringe 26, when thepiston rod 25 is driven by the rod driving actuator 24. Thus, the roddriving actuator 24 may be called a piston driving device. The syringe26 is provided with first to fourth ports 28, 29, 30 and 31 that connectthe inside of the syringe 26 to the outside. The first and second ports28 and 29 are located on one side of the piston 42, whereas the thirdand fourth ports 30 and 31 are located on the other side of the piston42. The first and third ports 28 and 30 are located on the top side ofthe syringe 26, whereas the second and fourth ports 29 and 31 arelocated on the bottom side of the syringe 26 in opposition to the firstand third ports 28 and 30 respectively.

[0047] The first and third ports 28 and 30 are connected to the two-wayswitching valves 13 and 14 respectively through Teflon tubes. Thetwo-way switching valves 13 and 14 are connected to the collection tank11 through Teflon tubes, and are switched over between an open positionand a closed position by means of switching actuators 33 and 34respectively. In the closed position, the two-way switching valves 13and 14 respectively disconnect the first and third ports 28 and 30 fromthe collection tank 11. The collection tank 11 is a hermetic tank with apressure regulation valve, and accepts air bubbles together with thelubricant when they are ejected from the syringe 26 for venting the airout of the syringe 26. Thus, the first and third ports 28 and 30 may becalled venting ports.

[0048] The second and fourth ports 29 and 31 are connected to thefour-way switching valve 12 through Teflon tubes. To the four-wayswitching valve 12 are also connected the supply tank 15 and the needlevalve 17 through Teflon tubes. The four-way switching valve 12 isswitched over between a forth movement position as shown in FIG. 2, anda back movement position as shown in FIG. 3. While the piston rod 25 isbeing moved forward, the four-way switching valve 12 is switched to theforth movement position where the fourth port 31 is connected to thesupply tank 15, and the second port 29 is connected to the needle valve17. While the piston rod 25 is being moved backward, the four-wayswitching valve 12 is switched to the back movement position, andconnects the second port 29 to the supply tank 15 and connects thefourth port 31 to the needle valve 17. The four-way switching valve 12is switched by driving a four-directional switching actuator 35.

[0049] The supply tank 15 is a hermetic tank with a pressure regulationvalve, and contains the lubricant. A mixing mechanism 38 is providedinside the supply tank 15, for mixing the lubricant to keep the densityof the lubricant constant. The mixing mechanism 38 for the supply tank15 has a magnet stirrer structure. The above described mechanisms,actuators and other elements are controlled totally by a control section40. It is to be noted that the Teflon tubes may be replaced by anothertype of tubes, such as plastic tubes or metal tubes, insofar as the tubematerial is suitable for the properties of the lubricant. The supplytank 15 is disposed in a higher position than the collection tank 11.

[0050] As shown in FIGS. 4 and 5, the syringe 26 is of a cylindricalshape, and is held horizontal. The syringe 26 has a symmetric internalstructure about a center plane including center axes of the cylindricalports 28 to 31. The syringe 26 has an internal diameter that isapproximately equal to an external diameter of the piston 42 at least ina range L in which the piston 42 is moved back and forth. An O-ring 43is put around the piston 42 at a center position in the axial direction,so as to close the clearance between the outer periphery of the piston42 and the inner periphery of the syringe 26. Large diameter sections 44and 45 having a larger diameter than the external diameter of the piston42 are formed on opposite sides of the piston 42. The large diametersections 44 and 45 have an axial length that is shorter than thereciprocation range L of the piston 42. The first and second ports 28and 29 are formed on the top and bottom sides of the large diametersection 44 respectively. The third and fourth ports 30 and 31 are formedon the top and bottom sides of the large diameter sections 45respectively.

[0051] The dispenser 16 is also provided with a mixing mechanism formixing or stirring the lubricant in the syringe 26, to keep ratio ofcomponents constant. The mixing mechanism is constituted of a pair ofstirrers 47 and 48, a pair of stirrer drive rings 49 and 50, and a pairof stirring actuators 51 and 52. The stirrers 47 and 48 have the samestructure, each having three stirring blades 53 or 54 and internalmagnets 55 or 56, as shown in detail in FIGS. 6 and 7. The stirrers 47and 48 are mounted on the piston rod 25 between the piston 42 and thelarge diameter sections 44 and 45, such that the stirrers 47 and 48 mayrotate around and slide along the piston rod 25 as well. Thus, thepiston rod 25 is driven to move the piston 42 back and forth between thestirrers 47 and 48. To avoid wearing the internal periphery of thesyringe 26 by friction between the stirrer 47 or 48 and the syringe 26,the stirrers 47 and 48 have a smaller external diameter than theinternal diameter of the syringe 26.

[0052] The stirrer drive rings 49 and 50 are disposed on the syringe 26in those positions around the stirrers 47 and 48 respectively, and aremounted through bearings to a syringe holder 58, such that the stirrerdrive rings 49 and 50 may rotate around the syringe 26. The stirrerdrive rings 49 and 50 are driven to rotate when driving forces aretransmitted from the stirring actuators 51 and 52 through gears 49 a and50 a that are formed around the outer periphery of the stirrer driverings 49 and 50 respectively. The stirrer drive rings 49 and 50 haveinternal magnets 59 or 60, as shown in detail in FIG. 8, so that thestirrer drive rings 49 and 50 hold the stirrers 47 and 48 in thoserelative positions to the stirrer drive rings 49 and 50, which aredetermined by the relative positions of the magnets 55 and 56 of thestirrers 47 and 48 to the magnets 59 and 60 of the stirrer drive rings49 and 50, even while the stirrer drive rings 49 and 50 are rotating.Thus, the stirrers 47 and 48 rotate following the stirrer drive rings 49and 50.

[0053] Referring to FIG. 6, each of the stirrers 47 and 48 has a hole 62formed through along the axial direction thereof, for putting the pistonrod 25 through the hole 62. The stirring blades 53 or 54 are provided onone face end of the stirrers 47 or 48 to protrude in the axial directionof the stirrers 47 or 48, that is, in parallel to the piston rod 25. Thethree stirring blades 53 or 54 are arranged radially around the hole 62at intervals of 120°. The stirrers 47 and 48 are mounted on the pistonrod 25 in the opposite directions from each other, with their stirringblades 53 and 54 oriented to the large diameter sections 44 and 45respectively.

[0054] As shown in FIG. 7, the magnets 55 and 56 are embedded incavities 63 which are formed inside the stirrer 47 or 48 with their openends oriented toward the center axis of the stirrer 47 or 48. Eachstirrer 47 or 48 has six cavities 63, three of which are arrangedradially around the center axis at intervals of 120°, and other threesare located on one side of these three cavities in the axial directionof the piston rod 25 in one-to-one alignment with the former threecavities. The magnets 55 and 56 are put into the cavities 63 throughholes 64 which are formed through the outer peripheries of the stirrers47 and 48 in diametrically opposite positions from the cavities 64. Themagnets 55 and 56 may be arranged in a different way from illustrated,insofar as they are arranged symmetrical about the rotary axis of thestirrer 47 or 48.

[0055] The stirrer drive rings 49 and 50 have the same structure. Asshown in FIG. 8, the magnets 59 and 60 are arranged in correspondencewith the magnets 55 and 56 respectively. That is, there are six magnets59 or 60 in each stirrer drive ring 49 or 50, three of which arearranged radially at intervals of 120°, and other threes are located onone side of these three magnets in the axial direction of the piston rod25 in one-to-one alignment with the former three magnets. Polarities ofthe magnets 55, 56, 59 and 60 are so arranged that the magnets 59attract the magnets 55, whereas the magnets 60 attract the magnets 56.According to this configuration, the stirrer 47 or 48 is held stationaryin the stirrer drive ring 49 or 50 while the stirrer drive ring 49 or 50stops, and rotates along with the stirrer drive ring 49 or 50 as thestirrer drive ring 49 or 50 rotates. It is possible to arrangepolarities of the magnets 55, 56, 59 and 60 such that the magnets 55 or56 repel the magnets 59 or 60 respectively.

[0056] Now the operation of the above described lubricant coating system10 will be briefly described.

[0057] The lubricant coating system 10 automatically operates accordingto a sequence stored in a memory 70 (see FIG. 1) of the control section40. There are a normal mode and a standby mode in the sequence, as shownin FIG. 9, and these modes are automatically switched over appropriatelydepending upon traffic of the pallets 19 on the conveyer line 20.Specifically, the normal mode is executed when the pallets 19 aresuccessively smoothly conveyed, whereas the standby mode is executedwhen the pallets 19 on the conveyer line 20 get jammed upstream ordownstream of the coating station, or when there are not any pallets 19upstream the conveyer line 20. Sensors 71 and 72 are disposed inupstream and downstream positions of the coating station, to detect thepallets 19 on the conveyer line 20.

[0058] In the normal mode, the dispensing operation is performed whilesetting the on-off valve 17 b of the needle valve 17 open. As shown inFIG. 10, at the start of the normal mode, it is checked whether thetwo-way switching valves 13 and 14 are set in the closed position, andif not, the valves 13 and 14 are switched to the closed position.Although it is not shown in the drawings, the position of the four-wayswitching valve 12 is also checked to confirm that the switching valve12 is set in either the forth movement position or the back movementposition.

[0059] Thereafter, upon receipt of the end-of-positioning signal, therod driving actuator 24 is driven to move the piston rod 25 in onedirection by a constant stroke. Then, a corresponding amount oflubricant is ejected through the needle valve 17, and is put on theobject to coat 18. One of the stirrers 47 and 48 that is placed in thesucking side of the syringe 26, e.g. the stirrer 48 in the forthmovement of the piston rod 25, is always rotated, whereas the otherstirrer in the ejection side of the syringe 26 is not rotated. Becausethe stirrers 47 and 48 can slide on the piston rod 25, the stirrers 47and 48 are held in the same relative positions to the stirrer driverings 49 and 50 by virtue of the magnets 55, 56, 59 and 60, even whilethe piston rod 25 is moved in the axial direction.

[0060] The rod driving actuator 24 drives the piston rod 25 to move inone direction by one stroke each time it receives the end-of-positioningsignal, to coat the object 18 with the constant amount of lubricant.When the piston rod 25 reaches a terminal of one moving direction, thecontrol section 40 controls the rod driving actuator 24 to change themoving direction of the piston rod 25. Correspondingly, the sucking sideand the ejecting side of the syringe 26 are exchanged, and the stirrer47 or 48 that has been rotating stops rotating, and the other stirrer 47or 48 starts rotating continually

[0061] Before starting the dispensing operation in the oppositedirection, a piston turning operation is executed. As shown in FIG. 11,the piston turning operation consists of a drip prevention step, aventing step, a valve switching step for the four-way valve 12, apre-stroking step, and a nozzle cleaning step.

[0062] In the drip preventing step, the switching values 12 to 14 stayin the same positions as in the preceding dispensing operation, but thepiston rod 25 and thus the piston 42 are moved slightly in the oppositedirection to the preceding moving direction. Since the piston rod 25 isfirst moved forward in the dispensing operation in this instance, theswitching valve 12 is set in the forth movement position, and theswitching valves 13 and 14 are set in the closed position, as shown inFIG. 12, and the piston rod 25 is moved slightly backward. Thereby, thelubricant is sucked through the second port 29 back to the syringe 26,so the lubricant remaining in the nozzle 17 a is prevented fromdripping.

[0063] The venting step follows the drip prevention step. In the ventingstep, the actuator 33 or 34 is driven to switch one of the two-wayswitching valves 13 and 14 that is on the sucking side in the precedingdispensing operation, i.e. the valve 14 in this instance, to the openposition for a limited time, as shown in FIG. 13. While the valve 14 isturned open, the piston rod 25 is moved by a predetermined stroke in theopposite direction to the preceding movement, i.e. in the backwarddirection in this instance. Since the supply tank 15 is disposed abovethe collection tank 11, the lubricant flows from the supply tank 15 intothe syringe 26 by itself, as the lubricant flows through the open valve14 out of the syringe 26 into the collection tank 11, because of thedifference in height between the supply tank 15 and the collection tank11. Thereby, bubbles that have been produced in the lubricant because ofnegative pressure inside the syringe 26 flow with the lubricant into thecollection tank 11, so the bubbles are eliminated from inside thesyringe 26. The stroke of the piston rod 25 propels venting the bubblescontained in the lubricant out to the collection tank 11. The stroke ofthe piston rod 25 for the venting step is determined smaller than thatfor the dispensing operation, but may be equal to or larger than thestroke for the dispensing operation.

[0064] Since the first and third ports 28 and 30 are formed on the topsides of the large diameter sections 44 and 45, and the air entering thesyringe 26 or the bubbles generated in the syringe 26 tend to cometogether in the top sides of the large diameter sections 44 and 45, thebubbles are efficiently exhausted. Venting or exhausting the bubblesprior to the dispensing operation prevents the bubbles from beingincreased by the dispensing operation, and thus facilitates making thedispensing operation in continuous succession. It is to be noted thatthe venting step may be executed only by opening one of the valves 13and 14 that is in the sucking side in the preceding dispensingoperation, without driving the piston rod 25.

[0065] After the venting step, either of the two-way switching valves 13and 14 is reset to the closed position, and the four-directionalswitching actuator 35 is driven to switch the four-way switching valve12 to the other position than before, i.e., to the back movementposition in this instance, as shown in FIG. 3. Thereby, the second port29 that has functioned as an ejection port in the preceding dispensingoperation is changed to a sucking port.

[0066] Thereafter, the pre-stroking step is executed by driving the roddriving actuator 24 to move the piston rod 25 and thus the piston 42 inthe backward direction by a small amount. Thereby, bubbles generated bythe switching of the four-way switching valve 12 are let out of thesyringe 26, and the lubricant is fed to the needle valve 17, driving outthe air that has been sucked into the needle valve during the dripprevention step. Simultaneously, the control section 40 drives a shiftmechanism 70 to insert an anti-sprinkle plate 71 into front of thenozzle 17 a, so that the lubricant from the nozzle 17 a may not besprinkled. After the shift mechanism 70 retracts the anti-sprinkle plate71 from the front of the nozzle 17 a, the cleaning mechanism 22 isactivated to clear the lubricant off the nozzle 17 a. Thereafter, thepiston rod 25 is moved by the constant stroke in the backward directionto dispense the lubricant. As described so far, since the piston rod 25is moved in the same direction in the piston turning operation as in thefollowing dispensing operation, the lubricant coating system 10 canstart the dispensing operation immediately. When the piston rod 25 andthus the piston 42 reach a terminal in the backward direction, thepiston turning operation is executed in the same way as set forth above,while moving the piston rod 25 in the same direction as in the followingdispensing operation.

[0067] As long as the normal mode is continued, the above describedoperations are repeated to put the lubricant on the objects to coat 18successively.

[0068] Although the stirring blades 53 and 54 protrude in parallel tothe piston rod 25 in the present embodiment, it is possible to inclinethe stirring blades 53 and 54 to the axial direction of the piston rod25, so as to cause the lubricant to whirl in the axial direction. Thestirring blades may be oriented in a perpendicular direction to the axisof the piston rod 25. The number of stirring blades 53 and 54 and thenumber of magnets 55, 56, 59 and 60 are not limited to the aboveembodiment, but may be modified appropriately. The arrangement of thestirring blades as well as the magnets in the stirrer may be modifiedappropriately.

[0069] Now the operations in the standby mode will be described. In thestandby mode, the control section 40 keeps on monitoring the sensors 71and 72, so that the lubricant coating system 10 may return to the normalmode as soon as it is allowed.

[0070] In the standby mode, as shown in FIG. 14, the stirring actuators51 and 52 are driven to rotate both of the stirrers 47 and 48 for a timeintermittently at regular intervals. One of the stirrers 47 and 48 thatis on the sucking side of the syringe 26 at the start of the standbymode continues rotating during the standby mode as in the normal mode.Therefore, strictly speaking, the other stirrer 47 or 48 is driven torotate intermittently during the standby mode. Thus, the density of thelubricant is maintained constant in the syringe 26.

[0071] When a predetermined long time has elapsed from the start of thestandby mode, the piston rod 25 is moved in the opposite direction tothe preceding moving direction for the sake of making the same drippreventing operation as described before with respect to the pistonturning operation. Thereafter, the valve member 17 a of the needle valve17 is closed, for preventing the lubricant from evaporating.

[0072] When the lubricant coating system 10 returns to the normal modefrom the standby mode after the valve member 17 a is closed, a recoveryoperation is executed. In the recovery operation, as shown in FIG. 15,the on-off valve 17 b is opened, and the piston rod 25 is moved byseveral strokes, to supply the lubricant to the needle valve 17, therebyto drive the air out of the needle valve 17. The number of strokes forthis operation is determined such that the lubricant is ejected from thenozzle 17 a without fail. The shift mechanism 70 is activated during therecovery operation, to insert the anti-sprinkle plate 71 in front of thenozzle 17 a. After the shift mechanism 70 retracts the anti-sprinkleplate 71 from the front of the nozzle 17 a, the cleaning mechanism 22 isactivated to clear the lubricant off the nozzle 17 a. Thereafter, thepiston rod 25 is moved by the constant stroke in the backward directionto dispense the lubricant.

[0073] In the above embodiment, the stirrers 47 and 48 are mountedrotatable on the piston rod 25. According to another embodiment, asshown in FIG. 16, a ring-like stirrer 83 is fitted in a groove 84 thatis provided around an inner periphery of a syringe 82, such that thestirrer 83 may turn around a piston rod 87 while being guided along thegroove 84. The groove 84 is formed by a recessed inner peripheralportion of the syringe 82 and a sleeve 88 that is fit in the syringe 82from its one end. In this embodiment, a number of stirring blades 86 areprovided at regular intervals on an inner periphery of the stirrer 83and are protruded radially inward to an extent that the stirring blades86 will not interfere with the piston rod 87. As shown in FIG. 16, it ispreferable to incline the stirring blades 86 to the axial direction ofthe piston rod 87, so as to cause the fluid to whirl in the axialdirection in the syringe 82.

[0074] Although the stirrer drive rings 49 and 50 that are rotatedaround the syringe 26 by the stirring actuators 51 and 52 are providedas a stirrer driving device for rotating the stirrers 47 and 48 in theabove embodiment, a stirrer driving device of the present invention maybe configured differently. For example, according to the secondembodiment shown in FIG. 16, a magnetic coil 80 and a control circuit 81constitute the stirrer driving device. The magnetic coil 80 isconstituted of a plurality of coils that generate rotary magnetic fieldsat three or four regularly spaced positions around the syringe 82. Thestirrer 83 has at least two magnets 85 in diametrically oppositecircumferential positions thereof, the magnets 85 generating magneticfields in the radial directions of the stirrer 83. The control circuit81 generates electric current for exciting the magnetic coils 80 inthose phases necessary for rotating the stirrer 83.

EXAMPLE

[0075] The syringe 26 is preferably formed from a non-magnetic material,such as resin, ceramic or glass. As the resin, transparent PFA(perfluoro-alkoxy fluoroplastics) is preferable. The stirrers 47 and 48are preferably formed from a resin or a ceramic. The stirrer drive rings49 and 50 are preferably formed from a non-magnetic material, such asresin or brass.

[0076] The lubricant coating system 10 of the above embodiment ispreferably applicable to a recycling system of a lens-fitted photo filmunit. In that case, a shutter mechanism of a used lens-fitted photo filmunit is assumed to be the object to coat 18. The lens-fitted photo filmunit is constituted of a main body that contains a photo filmstriptherein and has exposure mechanisms mounted thereon, and front and rearcovers that cover the main body portion from the front and rear sides.The exposure mechanisms include a taking lens, the shutter mechanism,and a winding lock mechanism, and are expected to be reused. Aswell-known in the art, the shutter mechanism consists of a shutter drivelever, a shutter blade, a shutter charging spring, and a returningspring. The shutter blade usually closes a shutter opening that islocated behind the taking lens, and may swing in a plane perpendicularto an optical axis of the taking lens. The shutter drive lever mayrotate on an axis that extends in a vertical direction of thelens-fitted photo film unit, and kicks the shutter blade as it rotatesfrom a charged position to a released position, causing the shutterblade to swing in a direction to open the shutter opening. The shuttercharging spring is hooked at one end on a spring holding portion of theshutter drive lever, and at the other end on a portion other than theshutter drive lever, such that the shutter charge spring urges theshutter drive lever to the released position. The returning spring urgesthe shutter blade to return to the initial position closing the shutteropening.

[0077] The used lens-fitted photo film unit is collected anddisassembled in a factory for recycling. In the recycling system, someparts are sorted to be recycled as materials, and other parts are reusedas it is for assembling a new product. As for the lens-fitted photo filmunit, since the main body is covered with the front and rear covers, themain body is little stained or damaged in most cases, so the main bodyis expected to be reused. Before reusing the main body, the exposuremechanisms are inspected to check if these mechanisms operate properly.According to the inspection, the speed of movement of the shutter bladetends to be changed depending upon under what conditions the collectedlens-fitted photo film unit has been used. But it has been found thatthe variations in the shutter speed can be reduced to a predeterminedtolerable range, without exchanging the parts, if only a lubricant isput on the engagement between the one end of the charging spring and thespring holding portion of the shutter drive lever. The lubricant coatingsystem 10 of the present invention is effectively usable for thispurpose. After being coated with the lubricant, the speed of the shutterblade is measured a number of times, to check if the speed variation isin the tolerable range.

[0078] As the lubricant, a liquid type lubricant that is composed of anoil component with a high fluidity at a low temperature, and anultrafine fluoroplastic is suitable for the shutter mechanism. Exemplaryof such liquid type lubricant is Dry Surf HF-1800 (trade name), producedby Herves Ltd. This lubricant is called a dry coating lubricant, looksopaque white, has no flash point in the open-cup flash point test, isusable in a range from −30° C. to 120° C., and has a specific gravity of1.25 at 25° C. After the coating, the surface of this lubricant ishalf-wet. Also, this lubricant includes no factor of destroying theozone, lasts for 4.1 years in the atmosphere, and the GWP is 500(CO²=1). Accordingly, this type of lubricant is highly volatile andcontains solid components, so the density will change while it is storedin a hermetic container. To keep the density constant, the abovedescribed lubricant coating system 10 provided with the mixing devicesis preferable. The amount of lubricant to put on the individual mainbody of the lens-fitted photo film unit is preferably 0.001 cc to 0.01cc.

[0079] Since the piston rod 25 is moved back and forth in the lubricantcoating system 10, the lubricant may be dispensed successively. Becausethe lubricant contains the solid components, the lubricant is beingstirred in the sucking side of the syringe 26 even during the dispensingoperation. Since the lubricant is highly volatile, the on-off valve 17 bof the needle valve 17 is closed when the standby mode continues for along time. However, the present invention is applicable not only todispensing the above described lubricant, but any kind of fluid may bedispensed by the dispenser of the present invention.

[0080] Meanwhile, it is very important to clear optical members off ofdusts, sands and stains, since these extraneous objects remarkably lowerthe optical performances. Because optical members of the lens-fittedphoto film unit, such as a taking lens and a finder lens, are morelikely to get stained or scratched, it is necessary to inspect theoptical members each individually before reusing them.

[0081] For this purpose, these lenses have conventionally been inspectedby naked-eyes on the basis of a limit sample, but this conventionalmethod is inefficient and is inferior in reliability. To solve thisproblem, Japanese Laid-open Patent Application No. 8-304052 discloses alens inspection device that scans the lens surface with a spot lightbeam across a constant direction, and photo-electrically detects lightthat is transmitted and scattered through the lens. Because thetransmitted light is scattered if the lens has any defect, e.g. getscratched or stained, the lens inspection device generates a defectsignal when the detected signal goes above a preset level. Thisinspection device makes it possible to detect strains or scratches onthe lens through comparison of the signal level with the preset level,and thus accomplish efficient and quantitative evaluation.

[0082] Since the above conventional inspection device scans a spot lightbeam along a line, the inspection cannot be so speedy. Besides, wherethe lens has a scratch or a strain in the scanning direction, thetransmitted light is little scattered so it is difficult to detect themaccurately.

[0083] Moreover, because the stain on the lens surface reflects ordeflects some fragment of the incident light, so the intensity of thetransmitted light is decreased. Therefore, an optimum photo-sensitivityfor detection of the stains is considered to be different from that fordetection of the scratches. However, since the above conventionalinspection device inspects any kinds of defects of the lens in the sameway, the reliability is unsatisfactory.

[0084] FIGS. 17 to 29 show a lens inspection system that permitsdetecting scratches, extraneous objects, such as stains, and other kindsof defects of an optical member with high accuracy. That is, accordingto the following embodiment, a light beam is projected from one sideonto a lens to inspect, and a light transmitted and scattered throughthe lens is photo-electrically detected as a dark field image of thelens on the other side of the lens, and when the intensity of thephotoelectric signal detected from an inspection range of aphotoelectric imaging device goes above a preset level, the lens isjudged to be defective.

[0085] In the present embodiment, the light is projected onto the entiresurface of the lens at once and a dark field image of the lens isphotographed through a photoelectric element. Therefore, the inspectionbecomes speedy. Since the defection sensitivity would not fluctuatedepending upon the direction of existence of the defects, any kinds ofdefects are detected without fail.

[0086] The lens inspection system according to the present embodiment isadapted to inspecting the taking lenses of the lens-fitted photo filmunits. As shown in FIG. 17, the lens inspection system for thelens-fitted photo film unit, hereinafter referred to as the inspectiondevice 110, is mainly constituted of a lens cleaner 111, a scratchdetector 112, an extraneous object detector 113 and a focus examiner117.

[0087] As shown in FIGS. 18 and 19, the scratch detector 112 and theextraneous object detector 113 are each provided with a light projector115 or 116 for projecting inspection light onto a taking lens 114, andan imaging device 120 or 121 that picks up electric signals from anoptical image of a convex surface 114 a of the taking lens 114,respectively. The taking lens 114 to inspect is held in a recess that isformed in a top surface of a specific pallet 122. The pallet 122 issuccessively conveyed by a not-shown pallet conveyer mechanism from thescratch detector 112 to the extraneous object detector 113.

[0088] Referring to FIG. 20 showing the scratch detector 112, the pallet122 holding the taking lens 114 is positioned in between the lightprojector 115 and the imaging device 120, with the convex surface 114 aof the taking lens 114 oriented upward. A substantially cylindricalaperture 123 is formed from the bottom of the recess through the bottomsurface of the pallet 122, so the inspection light from the lightprojector 115 is projected from the bottom side onto the taking lens114. To prevent eclipse of the inspection light from the light projector115, the aperture 123 has a smaller diameter on the side of the takinglens 114. In this instance, on condition that the pallet 122 has athickness of 8 mm, the aperture 123 has a diameter of 7.5 mm in on theside of the taking lens 114, and a diameter of 13 mm on the side of thelight projector 115.

[0089] The imaging device 120 is constituted of a CCD image sensor 124having photo sensor cells, called pixels, arranged in a two-dimensionalmatrix, a close-up ring 125 and an image forming lens 126 that areattached to the front of the CCD image sensor 124. The taking lens 114is positioned such that an optical axis C of the taking lens 114coincides with an optical axis of the image forming lens 126 and centersof the close-up ring 125 and the CCD image sensor 124. An optical imageof the taking lens 114 is formed through the image forming lens 126 on aphotoelectric conversion surface of the CCD image sensor 124, sophotoelectric signals whose intensities are proportional to theintensities of the incident light on the individual pixels are sent fromthe imaging device 120 to a scratch discriminator 130.

[0090] It is to be noted that the focal length of the image forming lens126 may be set in a range from 16 mm to 50 mm, and that the close-upring 125 is adjustable in a range from 6 mm to 40 mm. Also, a spacing L1between the top surface of the pallet 122 and the CCD image sensor 124may be set in a range from 30 mm to 200 mm. In this instance, the focallength of the image forming lens 126 is set at 50 mm, and the close-upring 125 is set at 30 mm, whereas the spacing L1 is set at 130 mm.

[0091] The close-up ring 125 is fixed in a distance L2 from the bottomsurface of the pallet 122. A not-shown red LEDs are built in theclose-up ring 125 to project the inspection light uniformly onto thetaking lens 114. A blinding mask 131 is mounted on a center of the lightprojector 115 so as to prevent inclusion of the light projector 115 inthe photographic field of the imaging device 120. That is, as shown inFIG. 5, direct rays of the inspection light which are projected in theaxial direction from the light projector 115 are prevented from fallingon the photoreceptive surface of the CCD image sensor 124. Only indirectrays which are scattered through the taking lens 114 may fall on thephotoreceptive surface. Accordingly, a dark field image of the takinglens 114 is formed on the CCD image sensor 124. Therefore, where thetaking lens 114 has no scratch, as shown in FIG. 21, the intensities ofthe photoelectric signals are lower than a predetermined level.

[0092] On the contrary, if there is a scratch 132 on the taking lens114, as shown in FIG. 22, some rays of the inspection light arescattered at the scratch 132, and is projected onto the CCD image sensor124. In that case, the intensities of the photoelectric signals fromthose pixels of the CCD image sensor 124, onto which the scattered lightrays fall are raised. Based on the photoelectric signals from the CCDimage sensor 124, the scratch discriminator 130 determines whether thetaking lens 114 gets any scratches or not. As shown for example in FIG.23, the scratch 132 is detected by the scratch discriminator 130 as alight area 133 having a corresponding size to the scratch 132. For thesake of showing the light area 133 conspicuously, it is drawn in blackin FIG. 23, whereas other dark area 34 is drawn in white. The blindingmask 131 may have a diameter L3 in a range from 10 mm to 20 mm insofaras it prevent the direct projection of the inspection light onto the CCDimage sensor 124. In this instance, the diameter L3 is 12 mm.

[0093] In the scratch discriminator 130, a round range on thephotoreceptive surface of the CCD image sensor 124, that is formed witha diameter of 6 mm about the optical axis C of the taking lens 114, isdefined to be an inspection range 138, and the signal intensities fromthose pixels which are included in the inspection range 138 arerepresented by 8-bit tonal levels (0 to 255). The scratch discriminator130 defines those pixels whose signal intensities are not less than“140” in the tonal level as light pixels, and checks if there is atleast a light area consisting of the light pixels of a predeterminednumber, e.g. 110 or more, in the inspection range. If there is, thescratch discriminator 130 judges that the taking lens 114 getsscratched. If not, the scratch discriminator 130 judges that there is noscratch on the taking lens 114.

[0094] In the present embodiment, the threshold tonal level for thelight pixel is set at “140”, and the threshold pixel number for thelight area is set at “110”. But these threshold values may be modifiedappropriately according to the required inspection accuracy. Even if anindividual scratch is so fine that it cannot be detected on the basis ofthe threshold values of the above embodiment, if there are a number ofscratches, the optical performance is lowered below a reusable level.Therefore, in order to improve the inspection accuracy, it is preferableto set up the scratch discriminator 130 such that 130 judges the takinglens 114 to be defective when there are more than a predetermined numberof fine scratches on the taking lens 114, as well as when there is alarge scratch on the taking lens 114.

[0095] As shown in FIGS. 19 and 24, the imaging device 121 of theextraneous object detector 113 is constituted of a CCD image sensor 135,a close-up ring 136 and an image forming lens 137 in the same way as forthe imaging device 120 of the scratch detector 112. The light projector116 of the extraneous object detector 113 is substantially circular, andis disposed above the taking lens 114 with its center on the opticalaxis C of the taking lens 114, when the pallet 122 holding the takinglens 114 is positioned in the extraneous object detector 113. That is,the light projector 116 is disposed between the pallet 122 and theimaging device 121. Not shown LEDs are built in the light projector 116,and inspection light is projected from a projection surface 116 a thatis formed around an inner periphery of the light projector 116 and isoriented toward the taking lens 114 when it is positioned in theextraneous object detector 113. Thus, the inspection light from thelight projector 116 is not directly projected onto the close-up ring125, but only indirect rays scattered at the taking lens 114 can fall onthe close-up ring 125. So the close-up ring 125 also takes a dark fieldimage of the taking lens 114.

[0096] If there is not an extraneous object on the taking lens 114, theinspection light passes through the taking lens 114, as shown in FIG.25, so the intensities of photoelectric signals from respective pixelsof the CCD image sensor 135 are low. On the contrary, if an extraneousobject 141 is on the taking lens 114, as shown in FIG. 26, some rays ofthe inspection light from the light projector 116 are scattered at thetaking lens 114 and fall on the photoreceptive surface of the CCD imagesensor 135. As a result, the intensities of the photoelectric signalsfrom those pixels corresponding to the position of the extraneous object141 on the taking lens 114 are increased. The photoelectric signals aresent from the imaging device 121 to an extraneous object discriminator140, so the extraneous object discriminator 140 determines based on thephotoelectric signals whether there is any extraneous object on thetaking lens 114 or not.

[0097] It is to be noted that the light projector 116 must have a largeenough internal diameter L4 for preventing inclusion of the lightprojector 116 in a photographic field of the imaging device 121.However, too large internal diameter L4 lowers the illuminance on thetaking lens 114 so much that the inspection accuracy is lowered. Forthis reason, the internal diameter L4 is preferably set in a range from130 mm to 180 mm. In this instance, the value L4 is set at 130 mm. Forthe same reason, a spacing L5 between the top surface of the pallet 122and the light projector 116 is preferably set in a range from 10 mm to30 mm. In this instance, the value L5 is set at 16 mm.

[0098] In the extraneous object discriminator 140, as shown in FIG. 27,a plurality of zones 142 having a width of 0.5 mm and extending indifferent diametrical directions are defined in an inspection range 144that corresponds to the lens surface and thus the dark field image ofthe lens surface, and each zone 142 are sectioned into a number ofrectangular segments 143 aligned in the diametrical direction. Eachsegment 143 has a length of 0.1 mm in the diametrical direction. Thesignal intensities from the pixels of the CCD image sensor 135 are alsoconverted into 8-bit data representative of “0” to “255” tonal levels inthe extraneous object discriminator 140. The extraneous objectdiscriminator 140 calculates a mean value of tonal levels (an averagetonal level) of those pixels which belong to the same segment 143. Thus,each segment 143 severs as an unit section of the inspection range 144.If a difference between the average tonal levels of adjacent two of thesegments 143 is above “120”, the extraneous object discriminator 140judges that some extraneous object is put on the taking lens 114. Whenthe difference in the average tonal level between the adjacent segments143 is less than “120” with respect to every segment, the extraneousobject discriminator 140 judges that there is no extraneous object onthe taking lens 114.

[0099] Although the threshold value of the difference between theaverage tonal levels of the adjacent segments 143 for judgement in theextraneous object discriminator 140 is set at “120” in the presentembodiment, the threshold value may be modified appropriately accordingto the required inspection accuracy. The size of the segments 143 mayalso be modified appropriately according to the fineness of theextraneous objects to detect.

[0100] Next, the operation of the lens inspection device 110 will bedescribed with reference to the flow chart of FIG. 28. Unit bodies ofused lens-fitted photo film units are disassembled and sorted intorespective components in an inspection factory. The taking lens 114 isseparated from the unit main body, and is subjected to a cleaning andblowing process, for removing dusts and fats off of the surface of thetaking lens 114.

[0101] After the cleaning and blowing process, the taking lens 114 isplaced on the pallet 122, to be conveyed to the scratch detector 112. Inthe scratch detector 112, the light projector 115 projects theinspection light from the bottom side of the pallet 122 onto the entiresurface of the taking lens 114 but diagonally to the optical axis C ofthe taking lens 114, so the imaging device 120 disposed above the takinglens 114 takes a dark field image of the taking lens 114. If there isany scratch on the taking lens 114, the inspection light is scattered atthe scratch, so some rays fall on the CCD image sensor 124. Thephotoelectric signals obtained by the CCD image sensor 124 are sent tothe scratch discriminator 130. The scratch discriminator 130discriminates the light pixels whose tonal levels are not less than“140”, and judges that the taking lens 114 has a scratch when there isan area consisting of not less than 110 successive light pixels. Thetaking lens 114 having any scratch may not be reused, so it is meltedand pelletized. If the taking lens 114 is judged to have no scratch, itis conveyed to the extraneous object detector 113.

[0102] In the extraneous object detector 113, the circular lightprojector 116 projects the inspection light from above and around theconvex surface 114 a of the taking lens 114, and the imaging device 121takes a dark field image of the taking lens 114. If there is anyextraneous object on the taking lens 114, the inspection light isreflected from the extraneous object and falls on the CCD image sensor135. The photoelectric signals obtained by the CCD image sensor 135 aresent to the extraneous object discriminator 140. The extraneous objectdiscriminator 140 detects differences in average tonal level betweenevery couple of adjacent segments 143, and judges that there is anextraneous object on the taking lens 114 when any of the differences isabove 120.

[0103] The taking lens 114 that is judged to have any extraneous objectis melted to be pelletized, or sent back to the cleaning and blowingprocess, and is inspected again. The taking lens 114 that is judged tohave no extraneous object is conveyed to the focus inspector 117. Afterpassing the inspection by the focus inspector 117, the taking lens 114is allowed to be reused.

[0104] In the above embodiment, the extraneous object discriminator 140defines the segments 143 in the diametrically extending zones 142 of theinspection range 144, as shown in FIG. 27. It is alternatively possibleto section the inspection range 144 into concentrically and radiallyinto sectors 145, as shown in FIG. 29, and calculate average tonallevels of the respective sectors 145. That is, each sector 145constitutes an unit section of the inspection range 144 in thisembodiment. The light source of the light projector 115 or 116 is notlimited to the LEDs, but may be another kind of light source, such as ahalogen lamp, insofar as it is able to project light uniformly onto theoptical member to inspect.

[0105] Projecting the inspection light simultaneously onto the entireobjective or image side surface of the lens achieves a quick inspectionon the lens defects as compared to the conventional method where theinspection light is scanned linearly across the lens. Also theinspection accuracy becomes independent of the direction the defectexits.

[0106] Doing inspection for scratches separately from inspection forextraneous objects permits setting up an optimum inspection sensitivityfor each kind of inspection. Since the inspection light is projectedonto the lens from either side, if a defect cannot be detected when theinspection light is projected from the bottom side, the defect may bedetected when the inspection light is projected from the top side.Especially because extraneous objects or stains are more likely to puton the objective side of the lens, inspection accuracy is remarkablyimproved by projecting the inspection light onto the objective side todetect extraneous objects or stains based on the reflected light fromthe objective side.

[0107] However, it is possible to execute either the inspection forscratches or the inspection for extraneous objects alone. Although theinspection for scratches is executed before the inspection forextraneous objects in the above embodiment, the sequence may bereversed. Covering the periphery of the scratch detector 112 and theextraneous object detector 113 with black light-shielding curtainsprotects the CCD image sensors 124 and 135 from ambient light, and thuscontributes to increasing the inspection accuracy.

[0108] The present invention has been described with respect to thetaking lens inspection device that inspects single-element convexlenses, the present invention is applicable also for inspection onconcave lenses or on lens systems composed of a plurality of lenselements, if only the optics are arranged to make it possible taking thedark field image.

[0109] Thus, the present invention is not to be limited to the aboveembodiments but, on the contrary, various modifications are possible tothose skilled in the art without departing from the scope of claimsappended hereto.

What is claimed is:
 1. A fluid dispenser having a syringe with ports onopposite ends thereof, a piston movable inside said syringe back andforth, and a supply tank being connectable alternately to one of saidports depending upon moving direction of said piston, said fluiddispenser dispensing a fluid from one of said ports that is located onthe end of said syringe toward which said piston is moving, whilesucking the fluid from said supply tank into said syringe through theother of said ports, said fluid dispenser comprising: a pair of stirrersprovided in said syringe on opposite sides of said piston, said stirrersbeing rotatable on a rotary axis that extends parallel to the movingdirection of said piston; and a pair of stirrer driving devices disposedon an outer periphery of said syringe in correspondence with saidstirrers, for driving said stirrers to rotate each individually by amagnetic force.
 2. A fluid dispenser as recited in claim 1 , whereineach of said stirrers has a plurality of magnets embedded thereinsymmetrically about said rotary axis of said stirrers, whereas saidstirrer driving devices generate magnetic fields that cause saidstirrers to rotate.
 3. A fluid dispenser as recited in claim 1 , whereinat least one of said stirrers is continuously rotated in one side ofsaid piston, into which the liquid is being sucked.
 4. A fluid dispenseras recited in claim 1 , further comprising: a piston rod that movestogether with said piston and extends on the opposite sides of saidpiston concentrically with said piston and said syringe; and a pistondriving device coupled to an end of said piston rod to move said pistonrod and said piston in either direction.
 5. A fluid dispenser as recitedin claim 4 , wherein said stirrers are mounted on said piston rod so asto be able to rotate around and slide along said piston rod.
 6. A fluiddispenser as recited in claim 5 , wherein said stirrers are kept in thesame axial positions in said syringe by the magnetic forces of saidstirrer driving device, while said piston rod is being moved back andforth together with said piston.
 7. A fluid dispenser as recited inclaim 5 , wherein each of said stirrers has a plurality of stirringblades on one end face thereof that is oriented away from said piston insaid syringe.
 8. A fluid dispenser as recited in claim 4 , wherein saidstirrers have a circular shape and are mounted in circular grooves thatare provided around an inner peripheral portion of said syringe oneither side of said piston, such that said stirrers are rotatable insaid grooves around the piston rod.
 9. A fluid dispenser as recited inclaim 8 , wherein each of said stirrers has a plurality of stirringblades on its inner periphery.
 10. A fluid dispenser as recited in claim4 , wherein said syringe and said piston rod are oriented horizontally,and venting ports are provided through upper portions of the oppositeends of said syringe, said venting ports being able to open and close,wherein at the time of turning the moving direction of said piston, oneof said venting ports that is on the side the liquid is just going to bedispensed from is turned open for a time immediately before the start ofdispensing.
 11. A fluid dispenser as recited in claim 10 , wherein saidone venting port is turned open while one of said ports that is on thesame end of said syringe as said one venting port is still connected tosaid supply tank.
 12. A fluid dispenser as recited in claim 10 , whereinsaid piston is moved by a stroke while said one venting port is open, ina direction to dispense the liquid from said one port.
 13. A fluiddispenser as recited in claim 10 , wherein said syringe has largediameter sections on the opposite ends, and said venting ports are eachlocated at a top portion of said large diameter section.
 14. A lensinspection method of inspecting a lens to determine whether said lens isdefective or not, said lens inspection method comprising the steps of:projecting an inspection light simultaneously onto an entire area ofsaid lens from one axial side of said lens such that a dark field imageof said lens is photographed by a photoelectric imaging device that isplaced on the other side of said lens, to detect those rays of theinspection light that are scattered at lens surfaces; and judging thatsaid lens is defective when photoelectric signals obtained from saidphotoelectric imaging device have intensities of more than apredetermined level at least across an area of said dark field image,and said area is larger than a predetermined size.
 15. A lens inspectionmethod of inspecting a lens to determine whether said lens is defectiveor not, said lens inspection method comprising the steps of: projectingan inspection light simultaneously onto an entire area of said lens fromone axial side of said lens such that a dark field image of said lens isphotographed by a photoelectric imaging device that is placed on saidone side of said lens, to detect those rays of the inspection light thatare reflected from a surface of said one side of said lens; calculatingan average intensity of photoelectric signals obtained from each of aplurality of unit sections that are defined in an inspection range ofsaid photoelectric image device, said inspection range corresponding tosaid dark field image; and judging that said lens is defective when adifference in said average intensity between adjacent two of said unitsections is above a predetermined threshold value.
 16. A lens inspectionmethod of inspecting a lens to determine whether said lens is defectiveor not, said lens inspection method comprising a first inspectionprocess comprising the steps of: projecting an inspection lightsimultaneously onto an entire area of said lens from one axial side ofsaid lens such that a dark field image of said lens is photographed by aphotoelectric imaging device that is placed on the other side of saidlens, to detect those rays of the inspection light that are scattered atlens surfaces; and judging that said lens has at least a scratch thereonwhen photoelectric signals obtained from said photoelectric imagingdevice have intensities of more than a predetermined level at leastacross an area of said dark field image, and said area is larger than apredetermined threshold value, and a second inspection processcomprising the steps of: projecting an inspection light simultaneouslyonto the entire area of said lens from said other side of said lens suchthat a dark field image of said lens is photographed by a secondphotoelectric imaging device that is placed on said other side of saidlens, to detect those rays of the inspection light that are reflectedfrom a surface of said other side of said lens; calculating an averageintensity of photoelectric signals obtained from each of a plurality ofunit sections defined in an inspection range of said photoelectricimaging device, said inspection range corresponding to said dark fieldimage; and judging that said lens has an extraneous object thereon whena difference in said average intensity between adjacent two of said unitsections is above a predetermined threshold value.
 17. A lens inspectiondevice for inspecting a lens to determine whether said lens is defectiveor not, said lens inspection device comprising: a photoelectric imagingdevice that is placed on one axial side of said lens and focused on saidlens; a lighting device disposed on the opposite side of said lens fromsaid photoelectric imaging device, for projecting an inspection lightsimultaneously onto an entire area of said lens from outside aphotographic field of said photoelectric imaging device; and a judgingdevice that judges said lens to be defective when photoelectric signalsobtained from said photoelectric imaging device have intensities of morethan a predetermined level at least across an area of said photoelectricimaging device, and said area is larger than a predetermined size.
 18. Alens inspection device as recited in claim 17 , wherein said lightingdevice has a blinding mask mounted on a front side thereof to prevententrance of the inspection light from said lighting device into saidphotographic field of said photoelectric imaging device.
 19. A lensinspection device for inspecting a lens to determine whether said lensis defective or not, said lens inspection device comprising: aphotoelectric imaging device that is placed on one axial side of saidlens and focused on said lens; a lighting device disposed on the sameside of said lens as said photoelectric imaging device, for projectingan inspection light simultaneously onto an entire area of said lens fromoutside a photographic field of said photoelectric imaging device; and acalculating and judging device for calculating an average intensity ofphotoelectric signals obtained from each of a plurality of unit sectionsof said photoelectric imaging device, to judge said lens to be defectivewhen a difference in said average intensity between adjacent two of saidunit sections is above a predetermined threshold value.
 20. A lensinspection device as recited in claim 19 , wherein said lighting devicehas a circular shape and projects the inspection light from a projectionsurface that is formed around an inner periphery of said lightingdevice.
 21. A lens inspection system comprising: a scratch detectingdevice comprising a photoelectric imaging device that is placed on oneaxial side of a lens to inspect and focused on said lens; a lightingdevice disposed on the opposite side of said lens from saidphotoelectric imaging device, for projecting an inspection lightsimultaneously onto an entire area of said lens from outside aphotographic field of said photoelectric imaging device; and a judgingdevice that judges said lens to have a scratch when photoelectricsignals obtained from an area of said photoelectric imaging device haveintensities of more than a predetermined level; and an extraneous objectdetecting device comprising a second photoelectric imaging device thatis placed on one axial side of said lens and focused on said lens; asecond lighting device disposed on the same side of said lens as saidphotoelectric imaging device, for projecting an inspection lightsimultaneously onto the entire area of said lens from outside aphotographic field of said second photoelectric imaging device; and acalculating and judging device that calculates an average intensity ofphotoelectric signals obtained from each of a plurality of unit sectionsof said second photoelectric imaging device, and judges said lens tohave an extraneous object when a difference in said average intensitybetween adjacent two of said unit sections is above a predeterminedthreshold value.